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    "# 主成分分析 PCA(Principal components analysis)\n",
    "## 数据降维 Dimensionality Reduction\n",
    "    指在某些限定条件下，降低随机变量的个数，得到一组“不相关”主变量的过程。例如有十七个指标，降维成三个新的指标（根据十七个指标的性质计算），准确率仍然很高。\n",
    "    从4D降到2D,实现可视化.\n",
    "## 主成分分析 主成分分析是数据降维技术中应用最多的方法\n",
    "    寻找K维新数据,使他们反应事物主要特征,在信息损失尽可能少的情况下\n",
    "    投影后不同特征数据尽可能分散。"
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